Abstract
The triplet saturable absorption behaviour of the xanthene dyes eosin Y. erythrosin B- and rose bengal and of the fullerene molecule C-70 is studied. The molecules are excited to the SI-state by intense picosecond pulses (wavelength lambda (P) = 527 nm). They relax dominantly to the triplet system by intersystem crossing. The triplet-triplet saturable absorption is investigated with time-delayed ...
Abstract
The triplet saturable absorption behaviour of the xanthene dyes eosin Y. erythrosin B- and rose bengal and of the fullerene molecule C-70 is studied. The molecules are excited to the SI-state by intense picosecond pulses (wavelength lambda (P) = 527 nm). They relax dominantly to the triplet system by intersystem crossing. The triplet-triplet saturable absorption is investigated with time-delayed intense picosecond pulses (wavelength lambda (L) = 1054 nm) in the transparency region of the molecules in the singlet ground state. Higher excited-state triplet absorption cross-sections and higher excited-state triplet relaxation times are determined by numerical simulation of the experimental results. Time-resolved fluorescence measurements reveal higher excited-state triplet to singlet back-intersystem-crossing and multi-step tripler photoionization. Additionally the two-photon absorption cross-sections at lambda (L) = 1054 nm are determined by measurement of the fundamental pulse two-photon induced fluorescence relative to the second-harmonic pulse single-photon induced fluorescence. (C) 2001 Elsevier Science B.V. All rights reserved.
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